The exterior walls of buildings are comprised of multiple elements that provide structural support and bracing as well as weather protection for the structure and the interior elements of the building. Typical structural elements include columns, beams, studs, and sheathing. Weather protection elements include siding, panel siding, trim, various cladding systems, and, in some cases, the sheathing. When used on the exterior of a building, sheathing may be applied to the outer face of studs, roof trusses, or rafters of the building to brace the structure, resist wind and other loads and to provide a backing for the exterior weatherproofing systems. In cases, the sheathing itself can serve as one of the weatherproofing elements of the building. Sheathing can be manufactured from a variety of materials including wood, cement, gypsum, insulation, foam insulation, or other suitable materials. Sheathing panels are typically attached directly to wall framing or roof framing members and are typically covered with a wall cladding, siding, or roofing. One example of sheathing is Oriented Strand Board (“OSB”). OSB is a wood and resin based sheathing product typically manufactured in four foot by eight foot sheets. The OSB sheathing is an engineered product used in wood frame construction in applications that historically used plywood or solid sawn wood members. OSB sheathing is typically manufactured with smooth or slightly roughened faces and can be used as a subfloor, roof sheathing, or wall sheathing, among other uses. When used as roof sheathing, the roughened surface of the OSB provides a slip resistant walking surface. When used as wall sheathing, the OSB is nailed or screwed to supporting wood framing. OSB sheathing is not oriented in a particular horizontal or vertical manner and can be cut into different sizes and shapes to sheath the underlying wood framing or furring.
Cladding may be formed from wood, “hardboard” or “pressboard,” plastics, cement, gypsum, insulation, foam insulation, or other suitable materials. Cladding is generally referred to as an external weatherproofing element that is attached to the exterior sheathing or framing. The cladding is typically applied over a weather resistant membrane (as used herein the term includes building paper, felt, house-wrap, and similar products including liquid or spray applied breathable coatings). In addition to siding, trim, and panel siding, cladding systems include stucco, brick, stone and other materials used to cover the building and provide weather protection. Trim, siding, panel siding, and other cladding systems can trap moisture behind the cladding systems resulting in degradation of the building paper, underlying sheathing, and the wood framing.
Cement board siding, wood siding, and ‘hardboard’ siding or ‘pressboard” siding are typically manufactured with a smooth ‘back’ or unexposed face, and a ‘front’ or exposed face, of the siding with a smooth finish or decorative patterns that simulate wood grain. Siding is a subset of cladding that is typically layered, or “lapped,” on the exterior surface of the structure to shed water. For siding, the typical installation of the siding is lapped with the upper pieces of siding overlapping the lower pieces of siding as the siding is installed up the typical exterior wall face. This lapped siding installation allows water to shed down the exposed face of the siding. The ‘back’ or un-exposed face of the siding is typically in contact with the underlying sheathing or building paper. The siding is nailed through the face of the siding, through the sheathing if present, and into the underlying wood framing (studs) of the wall assembly. Some water will reach the back side of the siding and/or the face of the building paper, during rain, snow, or condensation events. In traditional siding, at each level of the siding installation, the back side of the siding is tight against the building paper. At these contact points, or ‘pinch points’ the flow of water down the building paper is potentially obstructed. In addition, the ventilation of the space behind the siding is potentially obstructed. In traditional siding, the back of siding cannot ‘breathe’ resulting in potential degradation of the building paper, underlying sheathing, the wood framing.